System for supplying fuel to internal combustion engines

ABSTRACT

A system for supplying fuel to internal combustion engines by medium pressure injection including a pressurized fuel tank, a specially designed fuel pump and an electromagnetic fuel injector. The pump is a diaphragm-type pump of smaller diaphragm surface and increased spring pressure compared to conventional diaphragm-type fuel pumps. It is designed to provide an output fuel pressure at substantially that level necessary for feeding the injector thus obviating the necessity for a pressure regulator.

United States Patent Jaulmes 1 1 Aug. 26, 1975 [5 SYSTEM FOR SUPPLYINGFUEL TO 3,363,614 1/1968 Fisher 123/139 R INTERNAL COMBUSTION ENGINES3,724,435 4/1973 Bier 123/139 AV [75] Inventor: Eric Jaulmes, Paris,France FOREIGN PATENTS OR APPLICATIONS Assigneez Ateliers de laMotobecane, Pantin, 608,211 l/l935 France 123/139 France PrimaryExaminerWendell E. Burns [22] Filed: Dec. 5, 1973 AssistantExaminer.lames W. Cranson, Jr. pp NO: 421,870 Attorney, Agent, orfirm-Browdy and Nelmark [57] ABSTRACT Foreign Application Priority DataA system for supplying fuel to internal combustion en- Dec. 27, 1972France 72.46291 gines by medium pressure injection including apressurized fuel tank, a specially designed fuel pump and [52] US. Cl...123/139 A; 123/32 AE; 123/139 AW an electromagnetic fuel injector. Thepump is a dia- [51] Int. CL" F02M 39/00 phragm-type pump of smallerdiaphragm surface and [58] Field of Search 123/139 AH, 139 AV, increasedspring pressure compared to conventional 139 AW, 123/32 EA, 32 AEdiaphragm-type fuel pumps. It is designed to provide v an output fuelpressure at substantially that level nec- [56] References Cited essaryfor feeding the injector thus obviating the ne- UNITED STATES PATENTScessity for a pressure regulator.

2,062,644 12/1936 Ensign 123/139 AV 5 Claims, 7 Drawing Figures FUELTANK F 7 z AUXILIARY 5 l PUMP L ,5 INJECTOR I i l Iv l 1 PATENTED BZ3,901,204,

sum 2 UP 3 T A N K PUMP REGULATION CONTROL :9 J 1 [LI z 5 5 Q g i *2 E sd E a 25 2 I I 0 5 222g M Z Cm 2 E '5 (I 0 1' THE TANK Rflt CANNOT as JPRESSURIZED l I AP Venl'um @4 H n. g a: x E 8 2 z n: 8 f ,t w a g Q a zE g E ZKg/cm E a 6 5 THE TANK CANNOT BE PRESSURIZED l Mp IN NOZZLE 2PRESSURE IN TANK 1 I jog/cm 5 J E E 1 l LL 3 I l I Rflhn. PRESSURIZED lTANK I I g 5 u AP Venturl g E 2 5 m I d m 2 IL 3 75 5 3 6 i E I 2 z d Is fEgG E 5 5 1 d d a g 5 I: ZKg/Cm f =2 I g E 1 Rfltm. PRESSURIZED lTANK 1 {AP IN NOZZLE PATENTED AUBZB I975 saw 3 05 3 '1 PUMP FUEL TANKAUXIUARY INJECTOR SYSTEM FOR SUPPLYING FUEL TO INTERNAL COMBUSTIONENGINES FIELD OF THE INVENTION the high-pressure volumetric pump (feed)a discharge valve plus regulator (regulation) a controlled injector(control of flow).

3. The fuel line with a carburetor and pressurized present inventionrelates to a system for Supply 5 tank where the successive functions areaccomplished ing fuel to internal combustion engine by means of a by:fuel injector, and more particularly to an improved a Pressunzed tank(feed) I pump for supply fuel from a storage tank to the injecaFonstam'level chamber (regulahon) tor a et (control of flow).

. in all of these systems, presented for the sake of ex- BACKGROUND OFTHE INVENTION amples, there is a physical dissociation between the firsttwo functions due to the disproportion between lfhowh y m f g controlthe fuel feed the feed pressure and the required regulated pressure. fanlmemal combunshoh engme Perform three func- In conventional fuel linessupplying a carburetor of 3on5: i pp yv ff h and Control of type 1hereinabove, the properties demanded of the The Supply yfunctloh can beaccomplished either y pump mainly include ensuring flow at sufficientpresmeahs of 3 P p usually of the dlaphragm yp p sure for the fuel toenter a constant-level chamber h at a rathef 10W pressulje f the Order P200 g/cmzi which is generally located slightly above the pump, and y aPressurized tank z creates a 'P to limit the feed pressure when the jetis delivering a sure level to 30 y a Volumemc P p P- small volume so asnot to disturb the level in the float eratmg at a pressure level of theorder of several kiloh b m ln known fuel lines of type 2 hereinabove,the pump The regulation function can be accomplished eipressure ismuchgreater (possibly at least three times ther by means of a constant level(float) chamber or by as great) than the average pressure required tofeed the means of a pressure regulator, possibly associated withinjectors, and two pressure-limiting devices with rea discharge valve.turns to the tank are necessary.

The control of i flow function can be accompl shed. SUMMARY OF THEINVENTION by a fuel line which allows an amount to pass which is afunction of several parameters: pressure, cross- The Principal Object ofthe Present Invention 15 to section and opening time. Preferably, one ofthese pa- Provide a Simplified fuel line which pp gasoline t0 r r i m bnd d h others remain t t an engine whose carburetion is controlled by anorifice Thus, there is always a fuel supply system consisting Such thatv v of a pump, a pressure-regulating element which ensures The profilefi (needle'prolectfon h Seat) regulated f l pressure, d a controlelement which 2. The cross-section of the passageway is variable andserves to measure the amount of fuel fed into the cylin- ,comrolled(Opemng and the crosssectlon Versus d t x I travel of the needlerelationship).

F the Sake f an example, we can mention the 3. The downstream pressureis known (depression in lowing types of systems: the make nozzle) I v 4O4. The-upstream pressure 18 known and regulated to The com/6mm"?! fuelleading to the uwaconstant value, with the pressure being created by ator where the successive functions are carried Out by; diaphragm pumpconnected mechanically to the cra ka diaphragm pump (feed) 7 l shaft ofthe engine. its function is simultaneously to ena constant-level chamber(regulation) sure feed to the controlling element (electromagnetic a jet(control of flow) 7 injector) and to ensure a constant pressure in thefuel 2. The fuel injection system with electromagnetic line. control,where the successivefunc tions are carried out The following comparativetable summarizes the by: I j above.

. Conven. auto Conven. Conv. motorcy- Injection in carburetor Injectioncle carburetor accord. w/in- FIG. 3 FIG. 4 vention.FlG. 6

Pressurized Pressurized tank tank Feed Diaphragm Special Dia- Pumpphrugm pump Volumetric Pump Constant Constant level level Regulationchamber chamber Regulator Upstream Pressure Constant Constant ConstantConstant Down- Variable Variable Control stream depress. in depress. inof Pressuthroat of throat of flow re. Venturi Venturi C ross- Variableopensection ing crosssection Lifting ti- Lifting time Time me of adjusof adjusta table needle ble needle Hence, the invention consists inachieving a novel combination of a pressurized tank with a specialdiaphragm pump, designed, on the one hand, to function as a feed fromsaid tank, and, on the other hand, for the purpose of supplying aninjector at a constant pressure, as is always necessary, but withoutusing a regulating element. The injector is advantageously in conformitywith the following patent applications of the assignee:

French Pat. No. 2,205,111 for an electronic control and monitoringsystem for the feed of fuel to two-cycle fuel injection engines; and

French Pat. No. 2,206,795 for improvements made to fuel injectors forengines; both of which are hereby incorporated by reference.

Such a fuel supply line is characterized by a single average pressurelevel between the feed element and the control element, without anyadditional element for regulating the pressure.

A novel feature of the fuel line thus conceived consists in thedifferent operating conditions of the principal element, i.e., the pump.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be discussed ingreater detail with reference to the attached sketches:

FIG. 1 is an explanatory graph of fuel pressure as a function of flowfor the special diaphragm pump in accordance with the present inventionin comparison with a conventional diaphragm pump.

FIG. 2 is an explanatory graph showing the available flow from the pumpin accordance with the present invention as a function of the number ofstrokes per minute of the engine for a given pressure, and the maximumdemand of the engine.

FIG. 3 is a diagram indicating the pressures in the various portions ofa conventional automobile carburetor fuel supply system.

FIG. 4 is a diagram indicating the pressures in the various portions ofa conventional injection fuel supply system.

FIG. 5 is a diagram indicating the pressures in the various portions ofa conventional carburetor with pressurized tank fuel supply system.

FIG. 6 is a diagram indicating the pressures in the various portions ofa fuel supply system in accordance with the present invention; and

FIG. 7 represents as an example, in axial section, of a diaphragm feedpump in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS As is clearly shown by the graph inFIG. 1, the characteristic curve (at constant velocity) of the pressureas a function of the flow shows a favored zone (c) where the pumppressure remains constant while the flow remains below a certain levelD.

It is this property which is applied to the supply of the injectors bymeans of the present invention.

This zone narrows when the velocity drops but, fortunately, the needs ofthe engine follow the same law and consequently it is possible to adaptthe characteristic curve of the pump to the demand of the engine, asindicated by the graph in FIG. 2, where the available flow from the pumpfor various constant output pressures, on the one hand, and the maximumdemand of the engine on the other hand are represented as a function ofthe number of strokes per minute. There are four elements of adiaphragm-type fuel pump which must be adjusted for each application inorder to have the optimum compromise:

a. the force of the spring, which acts on the pressure; b. the effectivearea of the diaphragm, which affects the flow and the pressure; c. thetravel of the diaphragm, which also affects the flow; and

d. the mechanical linkage between the crankshaft and the pump, whichaffects the relative positions of the curves.

The pump designed according to the present invention, therefore,consists, on the one hand, of a diaphragm with a reduced area, in anaverage ratio of 3:1 (for example) in comparison to a conventional pump,and on the other hand a return spring for this diaphragm which isessentially more rigid than the conventional spring and which exercisesa force which is on the average twice as great.

In the pump according to the invention, the effective area of thediaphragm is at most 400 square millimeters and the force exercised bythe return spring is at least 3 kg. As an example, a pump designed for a350 cubic centimeter motorcycle engine has an effective diaphragm areaof 300 square millimeters and the force exercised by the spring amountsto 6 kg. The pump output pressure is 2 kg/cm and the flow is 12liters/hour for 2,500 strokes per minute.

For the sake of comparison, a conventional pump designed for al,000l,500 cubic centimeter automobile engine has an effective diaphragmarea of about 1,200 square millimeters and the spring exercises a forceof 1.5 kg. The pump output pressure is grams/cm and the flow is 25liters/hour at 1,000 strokes per minute. For the sake of an example, inFIG. 1 we have shown for 2,000 strokes/minute the characteristic curve(a) for the flow versus pressure for such a pump plotted with a dot-dashcurve, and the characteristic curve (b) of a classic pump plotted with adashed line.

On the other hand, since the diaphragm has a smaller area, but thestroke is comparable to that of conventional diaphragm pumps, the volumedisplaced with each cycle is low, although it is sufficient to satisfythe demand of the engine, and the gear ratio between the crankshaft andthe pump is therefore selected appropriately. This low volume, however,still does not allow the pump to assume in a satisfactory fashion(especially during starting), the function of aspiration from a tanklocated below the level of the pump and the pump is therefore combinedwith a tank located above the pump level.

Such a feed system at medium pressure for an electromagnetic injectorhas unquestionable advantages as follows:

1. Simplicity of design of a diaphragm pump relative to a fuel pump ofthe paddle type, with rollers or pistons, where tightness is obtained bymeans of accurate machining which is costly.

2. Regulation by the pump itself, doing away with any discharge valveassociated with a return line and intended to reduce the pressure levelto a lower level, called the regulated level.

3. Direct and mechanical connection to the crankshaft which makes itpossible to have independence relative to a battery, which may not existin the vehicle, with the application of energy to this linkagecorrespending exactly to the pumping needs, and the elimination of asafety element which is normally required in the event of electricalfeed in order to avoid useless pumping at very low speeds.

Means will preferably be included to eliminate gasoline vapor blocks inthe system in which the reservoir is located above the level of thepump. The lines will be provided with conventional means; the pumpadvantageously situated at a level which is very slightly above that ofthe injectors and a very low-volume bypass (very small diameter tube)which will connect the output and input.

This pump has associated with it a flexible hose which is used toeliminate the slight fluctuations in pressure in the line relative tothe average pressure level, playing the role of a capacitor, since theseslight fluctuations can occur when the injectors are working and whenthe pump diaphragm spring is put under ten- This resilient hoseconnected to injector 26, is represented by in P16. 7, which shows asimple example of a modified diaphragm pump according to the invention.

A cam 11 cut in shaft 12 driven by the engine crankshaft through thenecessary reduction gears acts on a push rod 13 which in turn moves arocker arm 14. The latter deforms diaphragm 15 which, according to theinvention, has a useful diameter which is significantly smaller thanthat of conventional diaphragms, its area being (for example) aboutthree times smaller. The return spring 16 of this diaphragm is itselfreinforced so as to exert a force which is about twice that of aconventional pump.

The intake nozzle is represented by 17 and the outlet nozzle isrepresented by 18. Valves 19 and 20 are associated respectively witheach of these two nozzles.

Nothing will be changed in the invention if the function of thepressurized tank 22 is ensured by an auxiliary pump 24 (shown in brokenlines because it is optional) which will furnish at the input of thespecial pump provided, a pressure level which is equivalent to that ofthis tank.

It will be obvious to those skilled in the art that various changes maybe made without departing from the scope of the invention and theinvention is not to be considered limited to what is shown in thedrawings and described in the specification.

What is claimed is:

l. A system for supplying fuel to internal combustion engines by mediumpressure injection, comprising:

a fuel tank;

a fuel injector;

a diaphragm-type fuel pump means for supplying fuel from said tank tosaid injector, said fuel pump means having an inlet, an outlet, adiaphragm and a spring return means;

linkage means for driving said fuel pump at a speed proportional to thatof the engine;

means for causing fuel from said fuel tank to enter the intake of saidfuel pump means at a predetermined pressure; and

line means for directly connecting the output of said fuel pump means tosaid injector without interposition of any pressure regulating means;

wherein the effective diaphragm area in said fuel pump means is at most400 square millimeters and the force exercised by said spring returnmeans is at least 3 kg,

whereby the fuel pump means output pressure will remain substantiallyconstant as the fuel pump means output flow varies from a substantiallynil value up to a predetermined maximum value.

2. A system according to claim 1, wherein the output pressure of saidfuel pump means is about 2 kg/cm 3. A system according to claim 1,wherein said line means connecting said fuel pump means to said injectoris resilient.

4. A system according to claim 1, wherein said means for causing fuel toenter the intake of said fuel pump means at a predetermined pressurecomprises means for locating said tank above the level of said pump.

5. A system according to claim 1, wherein said means for causing fuel toenter the intake of said fuel pump means at a predetermined pressurecomprises an auxiliary pump.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,901,204

DATED August 26 1975 INVENTOR(S) Eric Jaulmes It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

Column 6, line 38 (claim 4, line 4) "said means" should read -said fuelpump means-- Signed and Sealed this sixth D f January 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner of Patentsand Trademarks

1. A system for supplying fuel to internal combustion engines by mediumpressure injection, comprising: a fuel tank; a fuel injector; adiaphragm-type fuel pump means for supplying fuel from said tank to saidinjector, said fuel pump means having an inlet, an outlet, a diaphragmand a spring return means; linkage means for driving said fuel pump at aspeed proportional to that of the engine; means for causing fuel fromsaid fuel tank to enter the intake of said fuel pump means at apredetermined pressure; and line means for directly connecting theoutput of said fuel pump means to said injector without interposition ofany pressure regulating means; wherein the effective diaphragm area insaid fuel pump means is at most 400 square millimeters and the forceexercised by said spring return means is at least 3 kg, whereby the fuelpump means output pressure will remain substantially constant as thefuel pump means output flow vaRies from a substantially nil value up toa predetermined maximum value.
 2. A system according to claim 1, whereinthe output pressure of said fuel pump means is about 2 kg/cm2.
 3. Asystem according to claim 1, wherein said line means connecting saidfuel pump means to said injector is resilient.
 4. A system according toclaim 1, wherein said means for causing fuel to enter the intake of saidfuel pump means at a predetermined pressure comprises means for locatingsaid tank above the level of said pump.
 5. A system according to claim1, wherein said means for causing fuel to enter the intake of said fuelpump means at a predetermined pressure comprises an auxiliary pump.